Method and apparatus for descaling strip material



y 4, 1943 J. 5. STANIER E TAL 2,318,432

METHOD AND APPARATUS FOR DESCALING STRIP MATERIAL Filed Sept. 13, 1940 1 m n mm m S I n and Ernest B.Plo 1'1 Patented May 4, 1943 METHOD AND APPARATUS Fo DESCAIJNG STRIP MATERIAL John. S. Stanier and Ernest B; Plott, Youngstown, Ohio, assignors to The Youngstown Sheet & Tube Company, Youngstown, Ohio, a corporation of Ohio ApplicationSeptember 13, 1940, Serial No. 356,600

6 Claims.

This invention relates to the treatment of metallic strip and, in particular, to the removal of scale from ferrous strip or the like.

In the manufacture of sheet metal in strip form, e. g. steel strip, the strip is customarily pickled in an acid solution to remove the hotmill scale therefrom before the strip. is 'coldrolled. The pickling operation is objectionable because of the expense involved in constructing and maintaining large pickle tanks, to say nothing of the cost of the acid used. Various attempts have been made heretofore to obviate the acid pickling of ferrous sheet metal but none of them, so fas as we are aware, has been capable of satisfactorily removing the hot-mill scale to permit subsequent cold-rolling.

We have invented a novel method and apparatus for treating hot-rolled strip to remove the scale therefrom at a cost much below that of the conventional pickling process and at a speed higher than is practical in the latter. In a preferred embodiment and practice of our invention, we provide a, scale breaker and a brushing unit adapted to work on the strip progressively as it passes through the apparatus. In the scale breaker, the strip is bent back and forth to fracture the coating of scale and loosen it from the underlying metal after which brushes in the brushing unit engage opposite sides of the strip to positively dislodge. the loosened scale particles.

The preferred embodiment and practice of the invention are illustrated somewhat diagrammatically in the accompanying drawing, the single figure of which is a longitudinal, vertical section through the apparatus, showing a coil of strip in side elevation. Y

Referring now in detail to the drawing, the apparatus which We prefer to employ for carrying out the method of our invention comprises subjected may be varied. It will be apparent that strip from a coil l9 disposed on the supporting rolls I3, when passed around the rolls i5, i6 and H in the manner illustrated in the drawing, is progressively subjected to sharp bends in opposite directions. This progressive bending of the strip stretches the scale layer on opposite sides thereof to such an extent that it is fragmented and the bond between'it and the underlying metal loosened.

A roller leveler 20 is also mounted in the housing l8 and is adapted to' work on the strip after it has passed through the bending rolls i5, I6 and I1. The bending rolls deform the strip beyond the elastic limit and the roller leveler restores the strip to a substantially flat or level condition. The leveler 20 is of conventional construction, comprising a plurality of pairs of staggered rolls 2| by which the strip is bent back and forth to a progressively decreasing extent and is finally delivered substantially flat.

The brushing unit i2 comprises a plurality of staggered guide rolls 22 through 21. The rolls are arranged as illustrated so that the strip passing around them successively in the manner shown is bent in opposite directions. Rotary brushes 28 engage the strip as it passes around the rolls 23 through 26. The bristles of the brushes are at relatively high speed whereby both sides of the strip are subjected to a vigorous abrading an uncoiler III, a scale breaker II and a brushillustrated.

The scale breaker comprises staggered bending rolls l5, l6 and I1 journaled in suitable bearings (not shown) and enclosed in a housing l8 indicated diagrammatically. The bending roll l6 ispreferably mounted for vertical adjustment, as indicated by the dotted line position thereof, whereby the degree of bending to which the strip traveling around the rolls is action while bent convexly. This brushing effectively removes all the scale particles adhering to the strip after it is passed through the bending rolls l5, l6 and H and the roller leveler 20. As previously stated, the bending rolls cause fragmentation of the scale layers by the elongation thereof resulting from bending the strip in opposite directions which also loosensthe bond between the scale and the metal. By reasonof this result, it is possible for the rotary brushes effectively to remove the scale particles entirely, leaving the surfaces of the strip uniformly scalefree and in excellent condition for subsequent cold-rolling.

The bending rolls 22 through 21 and the rotary brushes 2! are preferably enclosedin a housing indicated diagrammatically at 29.

The strip 8 may be drawn from the coil I9 through the scalebreaker II and the brushing unit I! byany convenient means such as a pair of driven pinch rolls 30. Alternatively, the strip may be recoiled on any suitable form of coiler (not shown), It the strip is to be further reduced by cold-rolling, it will be recoiled. If the hot mill. In such case, the strip is preferably pulled through the apparatus by the pinch rolls 30 and delivered thereby directly to a suitable tank containing a light pickling solution.

It will be understood that in any case, successive coils will be attached end to end so they may be pulled successively through the apparatus shown without the necessity of rethreading each coil separately. i

It will be apparent from the foregoing description that the invention is characterized by numerous advantages. In the first place, the cost of the apparatus which we employ is much less than that of the numerous long pickling tanks which have been necessary heretofore for descaling strip. The maintenance cost of the apparatus shown is likewise much less than that of the acid pickling method. -A further important advantage is that our invention is capable of descaling strip at a relatively high speed, i. e., 300 feet per minute which is considerably higher than speeds ordinarily employed in the acid pickling of strip. As explained above, the invention may serve as a substitute for the entire acid pickling equipment or it may be used to treat the strip in advance of a light pickling, thereby making possible the passage of the strip through the pickling solution at a much higher speed than has been practical heretofore.

Although we have illustrated and described but a preferred embodiment and practice of the invention, it will be recognized that other arrangements and procedures may be employed within the scope of the appended claims.

We claim:

1; Apparatus for descaling strip comprising a roller leveler, staggered scale-breaking rolls on one side of the leveler adapted to bend the strip sharply in opposite directions, additional staggered rolls on the other side of the leveler adapted to bend the stripragain and brushes engaging the strip as it passes over said last-mentioned rolls.

2. In a method of removing tight scale from hot-rolled metal strip, the steps including subjecting the strip progressively while at substantially room temperature to sharp bends in opposite directions, thereby fragmenting the scale layers then subjecting the strip to a roller leveling operation, then again subjecting the strip to sharp bends in opposite directions whilebrushing each side of the strip at the point where it is convex thereby removing scale fragments remaining on the strip.

3. In a method of removing tight scale from hot-rolled metal strip, the steps including leading the strip about staggered rolls while at substantially room temperature thereby bending the strip progressively in opposite directions, roller leveling the strip, and brushing both sides of the strip progressively at the points where it is convexly bent.

4. In a method of removing tight scale from hot-rolled metal strip, the steps including leading the strip about staggered rolls while at substantially room temperature thereby bending the strip progressively in opposite directions, roller leveling the strip, again leading the strip about staggered rolls thereby bending it progressively in opposite directions and brushing the strip on both sides at points wher they are convex.

5. The method of removing scale from a metal sheet which comprises flexing such sheet sharply and simultaneously brushing the convex surface of such sheet normal to the line of flexing.

6. In a method of removing tight scale from hot-rolled metal strip, the steps including subjecting the strip progressively to sharp bends in opposite directions, thereby fragmenting the scale layers then again subjecting the strip' to sharp bends in opposite directions while brushing each side of the strip at the point where it is convex thereby removing scale fragments remaining on the strip.

JOHN S. STANIER. ERNEST B. PLOT'I'. 

